Today, it hit me that iOS is already ten years old. I consider iOS a relatively new and fresh operating system, but can we really say that at ten years old? In order to figure that out, I quickly threw together a little graph to visualise the age of both current and deprecated operating systems to get a better look at the age of operating systems.

It counts operating system age in terms of years from initial public release (excluding beta or preview releases) to the last release (in case of deprecated operating systems) or until today (in case of operating systems still in active development). I've included mainly popular, successful, consumer-oriented operating systems, leaving out more server or embedded oriented operating systems (such as UNIX and QNX), which tend to have vastly different needs and development cycles.

As far as the nomenclature goes, Windows 9x includes everything from Windows 1.0 to Windows ME, and Mac OS covers System 1 through Mac OS 9.2.2. Windows CE is currently called Windows Embedded Compact, but its line also includes Windows Phone 7, Windows Mobile, and Windows PocketPC.

Red indicates the operating system is no longer being developed, whereas green means it's still under active development. The only question mark in this regard is Windows CE; its latest release is Embedded Compact 2013 in 2013, and while I think it's still in development, I'm not entirely sure.

This graph isn't a scientifically accurate, well-researched, quotable piece of information - it takes many shortcuts and brushes several questions aside for brevity's sake. For instance, looking at the last official release doesn't always make sense, such as with Windows Service Packs or Mac OS X point releases, and I haven't even been entirely consistent with these anyway.

On top of that, the graph doesn't take months or weeks into account, and just counts everything in terms of years. Linux shouldn't technically be included at all (since it's just a kernel), and you can conceivably argue that, for instance, Mac OS X is older than its initial release in the form of 10.0 since it's so heavily based on NEXTSTEP. Amiga OS is also a bit of a stretch, since its development pace is slow and has even died down completely on several occasions. You could maybe possibly argue that BeOS is still in active development in the form of Haiku, but I consider Haiku a reimplementation, and not a continuation.

In any event, I originally wasn't planning on doing anything with this, but I figured I might as well publish it here since it's an interesting overview.

Aside from the number of years and questions posted by others, I'd like to see some additional entries. Focusing on consumer-grade operating systems, I'd say OS/2 is missing. OS/2 is arguably still maintained and just made a release this year.

I question the validity of 31 years of AmigaOS.

If you think OS/2 is missing, than AmigaOS is definitively valid.
There is even a new bugfix release recompiled from original source for the 68k branch by Hyperion from last year.
(If you don't want to consider the PPC reimplementation as the real real)